Co-reporter:Jinqiao Long;Zhirong Luo;Tianman Wang
Journal of Materials Science: Materials in Electronics 2017 Volume 28( Issue 1) pp:657-660
Publication Date(Web):20 August 2016
DOI:10.1007/s10854-016-5571-5
A series of SrZn2(PO4)2:Eu3+,Tb3+, Li+ phosphors were prepared by the solid-state method. The characteristic results indicate that there is effective energy transfer from Tb3+ to Eu3+ when excited at 393 nm, and Li+ can efficiently enhances emission of Eu3+ for SrZn2(PO4)2:Eu3+, Tb3+. The optimal contents of Tb3+, Li+ are 0.05 and 0.048, which the corresponding sample is SrZn2(PO4)2:0.02Eu3+, 0.05 Tb3+, 0.048Li+ and its I (peak area) of PL is as high as 3.36 times of that without Li+. SrZn2(PO4)2:0.02Eu3+, 0.05 Tb3+, 0.048Li+ is a potential red-emitting phosphor for UV-based white LED.
Co-reporter:Tianman Wang, Rong Nong, Yong Gao, Xuzi Zhang, Zanru Tan, Lipeng Jian, Sen Liao, Yingheng Huang, Huaxin Zhang
Materials Letters 2017 Volume 208(Volume 208) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.matlet.2017.04.098
•(NaCl)y wt@LiLa(MoO4)2: 0.05Eu3+ were synthesized with a simple coating method.•PL intensity can be enhanced as high as 1.79 times by coating NaF.•Enhancement PL intensity is a major effect, and decreasing R is a minor effect.•(NaCl)0.48 wt@LiLa(MoO4)2: 0.05Eu3+ was a phosphor with high R values (R = 8.29).•The enhancement effect is considered as the result of low phonon energy of NaCl.A series of NaCl@LiLa(MoO4)2:0.05Eu3+ (denoted as NaCl@LLMO:0.05Eu3+) were prepared by a simple coating method. Dual emission properties induced by coating NaCl are discussed. The influence of coating NaCl on the luminescence properties of Eu3+ ions were studied. The coating of NaCl results in much more influence on the emission intensities than on the R values (R = I2/I1, where I2 and I1 are the peak area of 5D0 → 7F2 and 5D0 → 7F1 emissions of Eu3+ ions, respectively) of Eu3+ ions in these samples. The optimal coating content of NaCl is 48 wt% with the corresponding sample (NaCl)0.48 wt@LLMO:0.05Eu3+,whose PL intensity is as high as 1.79 times of that without coating NaCl. (NaCl)0.48wt@LLMO:0.05Eu3+ is a potential red-emitting phosphor with high R values (R = 8.29) for blue light-based white LED.Download high-res image (105KB)Download full-size image
Co-reporter:Yong Gao;Qiwei Long;Rong Nong;Tianman Wang
Journal of Electronic Materials 2017 Volume 46( Issue 2) pp:911-916
Publication Date(Web):20 October 2016
DOI:10.1007/s11664-016-4950-2
A series of (NaMgPO4)0.98−x: \({\hbox{Eu}}_{0.02}^{3 + }\), \({\hbox{Al}}_{x}^{3 + }\) phosphors were prepared by the solid-state method. X-ray powder diffraction results confirm that the samples contain mixture phases of crystals. The doped effect of Al3+ on the photoluminescence properties of (NaMgPO4)0.98−x: \({\hbox{Eu}}_{0.02}^{3 + }\), \({\hbox{Al}}_{x}^{3 + }\) phosphors is discussed. The results indicate that two dependent curves of emission relative intensity and strain on Al3+ doping concentration are all Gaussian curves, and a high correlation is observed between emission relative intensity of Eu3+ and strain caused by Al3+. In other words, emission relative intensity of Eu3+ is enhanced with the increase of the strain. The enhanced mechanism of the strain is discussed. In addition, (NaMgPO4)0.98−x: \({\hbox{Eu}}_{0.02}^{3 + }\), \({\hbox{Al}}_{x}^{3 + }\) phosphors are electric dipole-dominated transition red phosphors. The optimal molar concentration of Al3+ for the samples is 9%, which (NaMgPO4)0.89: \({\hbox{Eu}}_{0.02}^{3 + }\), \({\hbox{Al}}_{0.09}^{3 + }\) is a potential candidate as the red-emitting phosphor for ultraviolet-based white light-emitting diodes.
Co-reporter:Tianman Wang;Yong Gao;Zhipeng Chen
Journal of Materials Science: Materials in Electronics 2017 Volume 28( Issue 16) pp:11878-11885
Publication Date(Web):20 May 2017
DOI:10.1007/s10854-017-6996-1
A series of K2TiF6:Mn4+, M2+ samples were prepared by the cation exchange method. Experimental results indicate that Mn4+ and Ti4+ can be quantitatively exchanged. Doped effects of M2+ (M = Mg, Ca, Sr, Ba, and Zn) on the fluorescent properties of the samples were discussed. The results indicated that the most intensities of the PLE and PL peaks come from a blank sample (K2TiF6:0.0253Mn4+). The sample of K2TiF6:0.0253Mn4+ contains perfect hexagonal phase micro-sticks with sizes about 0.5 × 0.5 × 3.0 μm, which its decay lifetime and the photoluminescence quantum yields are 5.2 ms and 94.04%, respectively. The chromaticity coordinates of K2TiF6:0.0253Mn4+ indicated that this phosphor was a potential candidate as a red-emitting component for blue light excited white LED devices. The method described here is a potential candidate for large-scale synthesis of K2TiF6:Mn4+ micro-sticks.
Co-reporter:Yao Xia, Yingheng Huang, Qiwei Long, Sen Liao, Yong Gao, Jianqun Liang, Jiajia Cai
Ceramics International 2015 Volume 41(Issue 4) pp:5525-5530
Publication Date(Web):May 2015
DOI:10.1016/j.ceramint.2014.12.128
A series of single-phase Eu3+, Tb3+, Bi3+ co-doped LaPO4 phosphors were synthesized by solid-state reaction at 800 °C. Crystal structures of the phosphors were investigated by X-ray diffraction (XRD). A monoclinic phase was confirmed. The excitation (PLE) and emission (PL) spectra showed that the phosphors could emit red light centered at 591 nm under the 392 nm excitation, which is in good agreement with the emission wavelength from near-ultraviolet (n-UV) LED chip (370–410 nm). The results of PLE and PL indicated that the co-doped Tb3+ and Bi3+could enhance emission of Eu3+ and the fluorescent intensities of the phosphors excited at 392 nm could reach to a maximum value when the doping molar concentration of Tb3+ and Bi3+ is about 2.0% and 2.0%, respectively. The co-doping Tb3+ and Bi3+ ions can strengthen the absorption of near UV region. They can also be efficient to sensitize the emission of Eu3+, indicating that the energy transfer occurs from Tb3+ and Bi3+ to Eu3+ ions. From further investigation it can be found that co-doping Tb3+ and Bi3+ ions can also induce excitation energy reassignment between 5D0–7F1 and 5D0–7F2 in these phosphors, and result in more energy assignment to 5D0–7F2 emission in LaPO4:Eu3+, Tb3+, Bi3+. Our research results displayed that La0.94PO4:Eu3+0.02, Tb3+0.02, Bi3+0.02 could be a new one and could provide a potential red-emitting phosphor for UV-based white LED.
Co-reporter:Yingheng Huang, Yao Xia, Qiwei Long, Sen Liao, Yu Li, Jianqun Liang, Jiajia Cai
Ceramics International 2015 Volume 41(Issue 2) pp:2607-2610
Publication Date(Web):March 2015
DOI:10.1016/j.ceramint.2014.10.012
Aluminum borate nanowires were synthesized in a molten salt method at 1100 °C in the air by using ammonium aluminum carbonate hydroxide (AACH) and H3BO3 as starting materials. The as-synthesized samples were examined by XRD and SEM. The results showed that Al18B4O33 nanowires with an orthorhombic structure were formed at 1100 °C. A self-catalytic mechanism was proposed for the growth mechanism of the nanowires on the basis of the experimental phenomena.
Co-reporter:Yingheng Huang, Yao Xia, Yu Li, Sen Liao, Qiwei Long, Jianqun Linang, Jiajia Cai
Advanced Powder Technology 2015 Volume 26(Issue 3) pp:861-867
Publication Date(Web):May 2015
DOI:10.1016/j.apt.2015.02.013
Highlights
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La0.9Ce0.05(LiMn)0.05PO4⋅0.92H2O was obtained via solid-state reaction at 60 °C.
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A green-yellow emitting phosphor, La0.9Ce0.05(LiMn)0.05PO4 was obtained from the precursor.
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The spin-forbidden transition of Mn2+ seem to be released by Li+ co-doped.
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The Eα was determined with two isoconversional iterative procedures.
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Three methods were used to comparative study the mechanisms.
Co-reporter:Qiwei Long, Yao Xia, Yingheng Huang, Sen Liao, Yong Gao, Jiaming Huang, Jianqun Liang, Jiajia Cai
Materials Letters 2015 Volume 145() pp:359-362
Publication Date(Web):15 April 2015
DOI:10.1016/j.matlet.2015.01.095
•Eu3+ doped (AMgPO4)1.00−x:Eu3+x (A=Li+, Na+, K+) phosphors were synthesized.•Na+ induced electric-dipole dominated transition (5D0→7F2) of Eu3+.•The as-synthesized samples can be excited by 392 nm near-UV light.•(NaMgPO4)0.94:Eu3+0.06 was a potential phosphor for UV-based white LED.A series of Eu3+ doped (AMgPO4)1.00−x:Eu3+x (A=Li+, Na+, K+) phosphors were prepared by the solid-state method. XRD results confirm that the samples contain mixture phases of crystals. Cation effect of Li+, Na+, K+ on the PL properties of (AMgPO4)1.00−x:Eu3+x phosphors is discussed. The results indicated that among the three cations, Na+ not only provides the most intensity of Eu3+ emission, but also produces electric-dipole dominated transition (5D0→7F2) and results to obtain the most red color. The optimized molar concentrations of Eu3+ for the three kinds of samples are 6, 8, 10%, which (NaMgPO4)0.92:Eu3+0.08 is a potential candidate as the red-emitting phosphor for UV-based white LED.
Co-reporter:Yao Xia;Yingheng Huang;Yu Li
Journal of Thermal Analysis and Calorimetry 2015 Volume 120( Issue 3) pp:1635-1643
Publication Date(Web):2015 June
DOI:10.1007/s10973-015-4548-6
Precursor, La0.85Ce0.05Tb0.05Yb0.05PO4·3.91H2O was synthesized via solid-state reaction at 60 °C. The experimental results show that the synthesized product is hexagonal La0.85Ce0.05Tb0.05Yb0.05PO4·3.91H2O, and monoclinic La0.85Ce0.05Tb0.05Yb0.05PO4 is a novel yellowish-green emitting phosphor, which can be obtained after calcining La0.85Ce0.05Tb0.05Yb0.05PO4·3.91H2O at 800 °C in air. Based on the isoconversional procedures, the values of activation energy Eα associated with the thermal decomposition of the precursor were obtained by using OFW, KAS, Starink, and Vyazovkin methods. The values of activation energy Eα indicate that the decomposition is single-step kinetic process. The most probable reaction mechanism was estimated by Mastplosts and nonlinear methods. Mechanism equations obtained from the two methods are the same, which the nonlinear method is more efficient than the Mastplosts method. The value of pre-exponential factor A was obtained based on of Eα and the reaction mechanism.
Co-reporter:Zhipeng Chen, Yao Xia, Sen Liao, Yingheng Huang, Yu Li, Yu He, Zhangfa Tong, Bin Li
Food Chemistry 2014 Volume 155() pp:81-86
Publication Date(Web):15 July 2014
DOI:10.1016/j.foodchem.2014.01.034
•The thermal decomposition kinetics was studied with advanced isoconversional method.•The two decomposition stages of curcumin are all single-step processes.•The mechanisms of the two stages were estimated with two nonlinear methods.•The mechanisms obtained from the two methods are the same.The results of TG/DTG when curcumin was used as the food colouring agent indicated that the processing temperature of the food should not exceed 190 °C. The decomposition process of curcumin involved two stages. The results of Eα values, determined by an advanced isoconversional method, showed that the two stages were both single-step processes. The most probable mechanisms of the two stages were estimated by using comparative and nonlinear model-fitting methods. The mechanisms obtained from the two methods are the same, which are the assumed random nucleation and its subsequent growth for stage I and one-dimensional diffusion for stage II, respectively. The values of pre-exponential factor A for both stages were obtained on the basis of Ea and g(α). Besides, some thermodynamic functions (ΔS≠, ΔH≠ and ΔG≠) of the transition state complexes for the two stages were also calculated.
Co-reporter:Yingheng Huang, Yao Xia, Sen Liao, Zhangfa Tong, Gang Liu, Yu Li, Zhipeng Chen
Ceramics International 2014 Volume 40(Issue 6) pp:8071-8079
Publication Date(Web):July 2014
DOI:10.1016/j.ceramint.2013.12.161
The precursor, ammonium aluminum carbonate hydroxide (AACH) was synthesized via solid-state reaction at 60 °C. The experimental results show that the AACH is orthorhombic NH4Al(OH)2CO3, and the calcined powder products are hexagonal platelets of α-Al2O3 which can be obtained from calcining AACH in molten salt at 1000 °C. The linear and nonlinear methods were used to calculate the activation energies of the thermal process of AACH. The calculated results indicated the decomposition process involved two stages which were single-step kinetic processes. The most probable reaction mechanisms of the two stages were estimated by two comparative methods. The values of pre-exponential factor A of the two stages were obtained on the basis of Eα and the reaction mechanisms.
Co-reporter:Qiwei Long, Yao Xia, Sen Liao, Yu Li, Wenwei Wu, Yingheng Huang
Thermochimica Acta 2014 Volume 579() pp:50-55
Publication Date(Web):10 March 2014
DOI:10.1016/j.tca.2014.01.016
•The values of Eα were determined with advanced isoconversional procedure.•Masterplots and nonlinear methods were used to study the mechanisms.•Mechanism equations obtained from the two methods are the same.•Nonlinear method is more efficient than Masterplots method.The hydrotalcite, Mg4Al2(OH)12CO3·3H2O, was synthesized via low-heating solid-state reaction at 80 °C. The thermal decomposition of Mg4Al2(OH)12CO3·3H2O experienced two stages. The apparent activation energy Ea was estimated with Vyazovkin procedure. The average values of Ea associated with the two stages were determined to be 110.9 ± 10.3, 140.3 ± 4.2 kJ mol−1, respectively, which the two stages are single-step kinetic processes. Masterplots and nonlinear methods were used to define the most probable reaction mechanisms of the two stages. The results show that the reaction mechanism functions of the two stages are as follows: (i) g(α) = (1 − α)−2 − 1, (ii) g(α) = (1 − α)−1/2 − 1, respectively. The values of pre-exponential factor A for the two stages were obtained on the basis of Ea and g(α). Besides, some thermodynamic functions (ΔS#, ΔH# and ΔG#) of the transition state complexes for the two stages were also calculated.
Co-reporter:Yu Li, Yao Xia, Sen Liao, Qiwei Long, Xingyun Zhao, Shasha Dai, Ke Lu
Materials Letters 2014 Volume 123() pp:112-115
Publication Date(Web):15 May 2014
DOI:10.1016/j.matlet.2014.03.034
•Bi3+, Sm3+ co-doped La0.99−xBixSm0.01PO4 were obtained from the precursors.•Three sharp, strong and splitting emission peaks are located at 562, 596 and 642 nm.•The optimized concentration of Bi3+ for La0.99−xBixSm0.01PO4 is 0.9 mol%.•The CIE chromaticity coordinates of the optimized phosphor are x=0.42 and y=0.39.•The optimized phosphor has a strong orange light emitting property.Bi3+, Sm3+ co-doped La0.99−xBixSm0.01PO4 polycrystalline samples were synthesized by calcining precursors at 800 °C in air. The precursors were obtained via low-heating temperature solid-state reactions. Crystal structures of the phosphor were examined with XRD and a pure phase was confirmed. The excitation spectra show that the phosphor can be efficiently excited by near-ultraviolet light, and the optimized concentration of Bi3+ is 0.9 mol%. Three sharp, strong, and splitting emission peaks are located at 562, 596, and 642 nm, corresponding to CIE (Commission International de l׳Eclairage) chromaticity coordinates x=0.42 and y=0.39, which indicate the orange light emitting property. So, the phosphor is promising in UV-LED chip-based white light-emitting diodes.
Co-reporter:Yingheng Huang;Yao Xia;Zhipeng Chen;Zhangfa Tong;Yu Li
Food Biophysics 2014 Volume 9( Issue 3) pp:277-284
Publication Date(Web):2014 September
DOI:10.1007/s11483-014-9351-6
The advanced isoconversional and nonlinear model-fitting methods were used to calculate the activation energies of the thermal process of polysaccharide iron complex (PIC). The results of TG/TDG indicate that the processing temperature of the food should not exceed 223 °C when PIC is used as a food additive. The calculated results indicated the decomposition process involved two stages. The region I in stage II is a kinetically complex process, while stage I and region II of stage II are all single-step processes. The most probable mechanisms for stage I and region II of stage II are chemical reaction and contracting sphere. Meanwhile, the most probable mechanism functions for region I of stage II were determined by using nonlinear model-fitting method. The results of nonlinear model-fitting method showed the most probable mechanism of the parallel reactions for region I of stage II were nucleation and branching nuclei.
Co-reporter:Yu He, Sen Liao, Zhipeng Chen, Yu Li, Yao Xia, Wenwei Wu, and Bin Li
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 5) pp:1870-1876
Publication Date(Web):January 11, 2013
DOI:10.1021/ie302743h
The precursor of LiCoPO4 was synthesized by solid-state reaction at low-heating temperature using LiOH·H2O and NH4CoPO4·H2O as raw materials. LiCoPO4 was obtained by calcining the precursor. Based on isoconversional procedure and the distributed activation energy model (DAEM), the activation energies calculated indicate that the thermal process involves two regions, of which Region II (α = 0.38–0.90) is a kinetically complex process but Region I (α = 0.10–0.38) is a single-step process. The most probable mechanism for the Region I is two-dimensional diffusion. The distributed activation energy model (DAEM) was applied to study the Region II of decomposition process of the precursor. The distributions of activation energy, f(Eα) and values of pre-exponential factor A of the Region II of the thermal decomposition of precursor were obtained on the basis of the DAEM. The reliability of the DAEM for the Region II was tested by the comparison between experimental plots and calculated plots. The results show that the prediction of DAEM is reliable.
Co-reporter:Yu Li, Qian Chai, Sen Liao, Zhipeng Chen, Yu He, Yao Xia, Wenwei Wu, Bin Li
Materials Chemistry and Physics 2013 Volume 142(2–3) pp:453-458
Publication Date(Web):15 November 2013
DOI:10.1016/j.matchemphys.2013.05.030
•The precursor of La0.9Ce0.05Tb0.05PO4 was obtained via solid-state reaction at 293 K.•A green emitting phosphor, La0.9Ce0.05Tb0.05PO4 was obtained by calcining the precursor at 973 K.•The Region II of the thermal decomposition of the precursor is a kinetically complex process.•The kinetics of the thermal decomposition was studied with isoconversional procedure and DAEM.The precursor, La0.9Ce0.05Tb0.05PO4·0.5H2O was synthesized via solid-state reaction at 333 K. The experimental results show that the synthesized product is orthorhombic La0.9Ce0.05Tb0.05PO4·0.5H2O, and monoclinic La0.9Ce0.05Tb0.05PO4 is a green emitting phosphor which can be obtained after calcining La0.9Ce0.05Tb0.05PO4·0.5H2O at 973 K in air. Based on the iterative isoconversional procedure, the values of activation energy Eα associated with the Region I and Region II of the thermal decomposition of the precursor were obtained, which demonstrates that the Region II is a kinetically complex process, and the Region I is a single-step kinetic process and can be described by a unique kinetic triplet [Eα, A and g(α)]. The most probable reaction mechanism of the Region I was estimated by the comparison between experimental plots and modeled results. The value of pre-exponential factor A of the Region I was obtained on the basis of Eα and the reaction mechanism. The distributed activation energy model (DAEM) was applied to study the Region II.
Co-reporter:Sen Liao, Xiaoping Yang, and Richard A. Jones
Crystal Growth & Design 2012 Volume 12(Issue 2) pp:970-974
Publication Date(Web):December 15, 2011
DOI:10.1021/cg201444p
Four hexanuclear lanthanide salen complexes [Ln6(L1)4(OH)4(MeOH)4]·2Cl·4MeOH (Ln = Nd (1), Tb (2)), [Eu6(L2)4(OH)4(MeOH)2(EtOH)2(H2O)2]·2Cl·3EtOH·H2O (3), and [Er6(L2)4(OH)4(EtOH)2(H2O)2]·2Cl·2EtOH·MeOH·H2O (4) are formed from the reactions of LnCl3·6H2O and flexible Schiff base ligands H2L1 and H2L2 (H2L1 = N,N′-bis(3-methoxysalicylidene)(propylene-2-ol)-1,3-diamine, H2L2 = N,N′-bis(salicylidene)(propylene-2-ol)-1,3-diamine). The structures of 1–4 were determined by single crystal X-ray crystallographic studies, and their luminescence properties were determined.
Co-reporter:Zhipeng Chen, Qian Chai, Sen Liao, Xia Chen, Yu He, Yu Li, Wenwei Wu, and Bin Li
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 26) pp:8985-8991
Publication Date(Web):June 14, 2012
DOI:10.1021/ie300774x
The single-phase KZn2(PO4)(HPO4) was synthesized via solid-state reaction at 80 °C using K3PO4·3H2O, K2HPO4·3H2O, and ZnSO4·7H2O as raw materials. The thermal decomposition of KZn2(PO4)(HPO4) experienced one step, which was the intramolecular dehydration of the protonated phosphate groups to form Zn2P2O7. The apparent activation energy Ea was estimated with six comparative isoconversional procedures. The average value of the apparent activation energy Ea associated with the thermal decomposition of KZn2(PO4)(HPO4) was determined to be 411.49 ± 14.37 kJ mol–1, which demonstrates that the thermal decomposition of KZn2(PO4)(HPO4) is a single-step kinetic process and can be described by a unique kinetic triplet [Ea, A, g(α)]. A new modified method for multiple rate isotemperature was used to define the most probable reaction mechanism g(α), and reliability of the used method for the determination of the kinetic mechanism was tested by the comparison between experimental plots and modeled results for every heating rate. The results show that the mechanism function is reliable. The value of pre-exponential factor A was obtained on the basis of Ea and g(α). Some thermodynamic functions (ΔS⧧, ΔH⧧, and ΔG⧧) of the transition state complex were also calculated.
Co-reporter:Zhipeng Chen, Qian Chai, Sen Liao, Yu He, Yu Li, Xiahong Bo, Wenwei Wu, Bin Li
Thermochimica Acta 2012 Volume 543() pp:205-210
Publication Date(Web):10 September 2012
DOI:10.1016/j.tca.2012.05.027
The single phase NH4CoPO4·H2O with layered structure was prepared via solid-state reaction at 60 °C. Based on the iterative isoconversional calculation procedure, the values of activation energy Ea associated with the first, second and third stages of the thermal decomposition of NH4CoPO4·H2O were obtained, which demonstrate that the three stages are all a single-step kinetic process and can be adequately described by a unique kinetic triplet. The most probable reaction mechanisms of the three stages were estimated by comparison between experimental plots and modeled plots. The values of pre-exponential factor A of the three stages were obtained on the basis of Ea and the reaction mechanisms.Highlights▸ NH4CoPO4·H2O was prepared via solid-state reaction at 60 °C under normal pressure. ▸ The thermal decomposition of NH4CoPO4·H2O experienced three stages. ▸ Values of activation energy of the three stages were studied using iterative procedure. ▸ The kinetic mechanisms and A of the three stages were studied using an efficient techniques.
Co-reporter:Qian Chai, Zhipeng Chen, Sen Liao, Yu He, Yu Li, Wenwei Wu, Bin Li
Thermochimica Acta 2012 Volume 533() pp:74-80
Publication Date(Web):10 April 2012
DOI:10.1016/j.tca.2012.01.019
The LiZn0.9PO4:Mn0.1·H2O was synthesized via solid-state reaction at room temperature using LiH2PO4·H2O, ZnSO4·7H2O, MnSO4·H2O and Na2CO3 as raw materials.The experimental results show that the synthesized product is orthorhombic LiZn0.9PO4: Mn0.1·H2O, monoclinic LiZn0.9PO4:Mn0.1 is a green-yellow emitting phosphor which can be obtained after calcining LiZn0.9PO4:Mn0.1·H2O at 600 °C in air. Based on the iterative iso-conversional procedure, the average values of the activation energies associated with the thermal dehydration of LiZn0.9PO4:Mn0.1·H2O, was determined to be 90.28 kJ mol−1. Dehydration of the crystal water molecule of LiZn0.9PO4:Mn0.1·H2O is single-step reaction mechanism. A method of multiple rate iso-temperature was used to determine the most probable mechanism g(α) of the dehydration step. It is Mample single model (g(α) = −ln(1 − α)) and is controlled by random nucleation and subsequent growth mechanism. The pre-exponential factor A was obtained on the basis of Ea and g(α). Besides, the thermodynamic parameters (ΔS≠, ΔH≠, and ΔG≠)) of the dehydration reaction of LiZn0.9PO4:Mn0.1·H2O were determined.Graphical abstractThe LiZn0.9PO4:Mn0.1·H2O was synthesized via solid-state reaction at room temperature using LiH2PO4·H2O, ZnSO4·7H2O, MnSO4·H2O and Na2CO3 as raw materials. Study of the non-isothermal decomposition of LiZn0.9PO4:Mn0.1·H2O was carried out by thermogravimetry. The thermal decomposition mechanisms and associated kinetics have been investigated.Highlights► LiZn0.9PO4:Mn0.1·H2O was obtained via solid-state reaction at room temperature and normal pressure. ► The thermal process of LiZn0.9PO4:Mn0.1·H2O experienced two steps. ► Thermal dehydration of LiZn0.9PO4:Mn0.1·H2O is random nucleation and subsequent growth mechanism. ► The activation energies for the thermal decomposition of LiZn0.9PO4:Mn0.1·H2O were determined. ► The calcined product, LiZn0.9PO4:Mn0.1 is a green-yellow emitting phosphor.
Co-reporter:Sen Liao;Gang Liu;Xiaozhen Tian;Xia Chen;Wenwei Wu ;Yugui Liang
Chinese Journal of Chemistry 2010 Volume 28( Issue 1) pp:50-54
Publication Date(Web):
DOI:10.1002/cjoc.201090034
Abstract
A simple and novel route was provided for the preparation of the hexagonal Co(II)-substituted sodium zincophosphate (CoZnPO-HEX), which was obtained with ZnSO4·7H2O, CoCl2·6H2O and Na3PO4·12H2O as raw materials and polyethylene glycol-400 (PEG-400) as a surfactant via a one-step solid-state reaction at low heating temperature (60°C), and characterized with X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectra, thermogravimetric analysis and the 1st derivative of thermogravimetric analysis (TG/DTG) and transmission electron microscopy (TEM). The experimental results showed that the CoZnPO-HEX was selectively formed via this reaction at ambient temperature in the presence of PEG-400.
Co-reporter:Sen Liao, Zhi-Peng Chen, Xiao-Zhen Tian, Wen-Wei Wu
Materials Research Bulletin 2009 44(6) pp: 1428-1431
Publication Date(Web):
DOI:10.1016/j.materresbull.2008.10.018
Co-reporter:Sen LIAO;Wen-Wei WU;Ya-Bo SUN ;Bao-Ling SONG
Chinese Journal of Chemistry 2008 Volume 26( Issue 2) pp:281-285
Publication Date(Web):
DOI:10.1002/cjoc.200890055
Abstract
A simple and novel route for the preparation of chiral sodium zincophosphate (NaZnPO4·H2O) (CZP) was studied, and the target product was obtained with Na3PO4·12H2O and ZnSO4·7H2O as raw materials and polyethylene glycol-400 (PEG-400) as a surfactant via one step low heat solid state reaction. The product was characterized with TG/DTG, XRD, TEM and SEM. The experimental results showed that the NaZnPO4·H2O, which was all obtained from different P/Zn atomic ratios (0.9–1.15) of Na3PO4·12H2O to ZnSO4·7H2O and different ageing time (2.0–8.0 h) at 60 °C, had the same chiral crystal structures except slight difference in their crystallinity. The comparison experimental results suggest that the ageing temperature and anion control the enantiomorphism of NaZnPO4·H2O, that is, if ZnSO4·7H2O or Zn(NO3)2·6H2O were used as Zn source, the first chiral structure of space group P6122 was formed when the reaction mixture was aged at 60 °C, and the second chiral structure of space group P6522 was got when the reaction mixture was aged at room temperature.
Co-reporter:Sen LIAO;Xiao-Zhen TIAN;Wen-Wei WU;Xia CHEN;Tian-Shun WANG ;Jiang-Tao LI
Chinese Journal of Chemistry 2008 Volume 26( Issue 10) pp:1837-1842
Publication Date(Web):
DOI:10.1002/cjoc.200890331
Abstract
A simple and novel route for the synthesis of layered sodium hydrogen zinc phosphate, NaH(ZnPO4)2, was studied, and the target product was obtained with Na2HPO4·12H2O and Zn(NO3)2·6H2O as raw materials and polyethylene glycol-400 as a surfactant via a one step solid state reaction at 60 °C. The product was characterized with XRD, TG/DTG and FTIR. The experimental results showed that the NaH(ZnPO4)2 had only one major step of weight loss for dehydration of HPO42− into P2O74− ions at around 500 °C, so it had enough thermal stability to use as heterogeneous catalyzer for organic reactions. The comparison experimental results suggested that aging temperature control the products of the synthesis, that is, the NaH(ZnPO4)2 was formed when the reaction mixture was aged at 60 °C, and the α-Zn3(PO4)2·4H2O was obtained when the reaction mixture was aged at room temperature.
