•Solubility limit of Ce + Gd in the IBP glass is about 8 mol%.•Incorporation of Ce + Gd increases the fraction of Q0 and Q1, but decreases Q2 groups.•Density and Tg increase with the addition of Ce + Gd in the glass formation range.•Incorporation of Ce + Gd decreases the thermal stability of the IBP glasses.In this paper, effect of Ce + Gd incorporation on the structural features and properties of iron borophosphate (IBP) glasses was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and differential scanning calorimetric (DSC) measurements. The results show that the solubility limit of Ce + Gd in the IBP glass with the composition of 36Fe2O3-10B2O3-54P2O5 is about 8 mol%. The structural networks of the Ce + Gd containing IBP glasses consist predominantly of orthophosphate, Q0, groups and pyrophosphate, Q1, groups, along with [BO4] units and a small amount of metaphosphate, Q2, groups. The Ce + Gd incorporation increases the density and Tg but decreases thermal stability of the IBP glass. However, the thermal stability of the Ce + Gd doped IBP glasses increases with Ce + Gd until the contents of Ce + Gd nearly reach the limit solubility. Moreover, the incorporation of Ce + Gd offers depolymerizing effect on the glass networks, which increases the fraction of Q0 and Q1 groups, and decreases the fraction of Q2 groups. The conclusions provide researchers with useful information to understand the roles of Ce + Gd in iron-boron-phosphate based glasses for high-level nuclear waste immobilization.

•Crystallization kinetics of IBP based compounds has been investigated.•Ec for P1 and P2 are 211.77 KJ·mol−1 and 564.31 KJ·mol−1 respectively.•Eg decreases for IBP glasses with CeO2 doping but increases due to preexisting CePO4.•Ec insignificantly changes for P1 but increases for P2 as CeO2 doping for IBP glass.•Ec slightly increases for P1 but obviously decreases for P2 while CePO4 preexisting.Effects of CeO2 doping and the preexisting formed CePO4 crystallite on the crystallization kinetics and glass transition kinetics of the 36Fe2O310B2O354P2O5 glass (IBP glass) have been investigated by differential thermal analysis (DTA). The results reveal that a well defined glass transition peak and two crystallization peaks are observed in DTA curve of the IBP glass. The crystallization activation energies for the first crystallization peak (Ec for P1) and the second crystallization peak (Ec for P2) of the IBP glass are 211.77 KJ mol−1 and 564.31 KJ mol−1 respectively. And CeO2 doping insignificantly affects the Ec for P1 but increases the Ec for P2. Moreover, the preexisting CePO4 crystallite increases the Ec for P1 and the activation energies of glass transition peak (Eg). However, the CePO4 crystallite obviously decreases the Ec for P2. In addition, the crystal growth in the IBP glass occurs in two dimensions. Due to the preexisting CePO4, the dimensions of crystal growth in CeO2-doped IBP compounds change to three. The conclusions offer some useful information for the disposal of high-level radioactive wastes using iron borophosphate glasses and iron borophosphate based glass-ceramics.

•The solubility limit of Cr2O3 in the iron borophosphate glass is 1 wt.%.•β-CrPO4 and Fe2(HPO3)3 form when doped Cr2O3 content is more than 1.0 wt.%.•The addition of Cr2O3 leads to the conversion of Q0 units to Q1 units.•Tg is improved by Cr2O3 in the glass forming range.The structure and properties of the iron borophosphate glass containing different amount of Cr2O3 have been investigated by differential thermal analysis (DTA), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. It is found that the iron borophosphate glass containing less than 1 wt.% Cr2O3 is fully amorphous. Partial crystallization occurs when the content of Cr2O3 is more than 1.0 wt.%, and the main crystalline phases are β-CrPO4 and Fe2(HPO3)3. FTIR spectra and Raman spectra show that the structure of the studied Cr2O3-doped iron borophosphate glasses predominantly consists of orthophosphate (Q0) units and pyrophosphate (Q1) units along with [BO4] units. With the increase of Cr2O3, Q0 units gradually transform to Q1 units, and the addition of Cr2O3 leads to the formation of Cr–O–P bonds in the structural networks of the studied glass. The densities and glass transition temperature increase with the increment of Cr2O3 content up to 1.5 wt.%, suggesting that the glass networks are strengthened by Cr2O3 doping. The conclusions provide an improved understanding of the role of Cr2O3 in the structure of iron borophosphate glasses.

•Monazite GdPO4 are identified in the IBP glasses containing up to 6 mol% Gd2O3.•RL of the Gd2O3-loaded IBP glasses/glass-ceramics are about 10−2 g m−2 d−1.•Existence of GdPO4 does not degrade aqueous chemical durability of the IBP glass.•Tg increases with increasing Gd2O3 content in glass formation range.•IBP glasses are potential hosts for the immobilization of Pu3+ containing HLWs.Immobilization of gadolinium (Gd), a nonradioactive surrogate for Pu3+, in iron borophosphate glasses/glass-ceramics (IBP glasses/glass-ceramics) has been investigated. The IBP glass containing 4 mol% Gd2O3 is homogeneously amorphous. At higher Gd2O3 concentrations, additional Gd is retained in the glasses as crystalline inclusions of monazite GdPO4 crystalline phase detected with X-ray diffraction. Moreover, Gd2O3 addition increases the Tg of the IBP glasses in glass formation range, which is consistent with the structural modification of the glasses. The structure of the Gd2O3-loaded IBP glasses/glass-ceramics is mainly based on pyrophosphate units. The chemical durability of Gd2O3-loaded IBP glasses/glass-ceramics is comparable to widely used borosilicate glass waste forms and the existence of monazite GdPO4 crystalline phase does not degrade the aqueous chemical durability of the IBP glasses/glass-ceramics. The Gd-loading results imply that the solubility should not be a limiting factor in processing nuclide Pu3+ if the formed crystalline phase(s) have high chemical durability.

•Partial crystallization occurs in iron sodium glasses containing more than 6 mol% ZrO2.•The main crystal is ZrP2O7 when ZrO2 exceeds its solubility in iron sodium glass.•The main structure units of the ZrO2 doped iron sodium glasses are Q1 units.•4 mol% ZrO2 contained glasses have high thermodynamic and kinetic stability.The crystallization kinetics and structural properties of iron sodium phosphate glasses with different ZrO2 content are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and the differential scanning calorimetry (DSC). XRD data and EDS identify that the glasses containing 6 mol% ZrO2 shows partial crystallization and zirconium phosphate (ZrP2O7) phase is observed. Moreover, the glass transformation temperature (Tg) and the crystallization exothermal peak temperature (Tp) have maximum value for the iron sodium phosphate glasses containing 4 mol% ZrO2. Crystallization kinetic of the studied samples is studied using Kissinger and Augis-Bennett models. The activation energies for glass transition (Eg) and crystallization (Ec) increases with increasing content of added ZrO2, but these values begin to decrease when the content of ZrO2 exceeds 4 mol%. Two crystalline phases (ZrP2O7 and NaFeP2O7) are detected in the samples annealed at 900 °C for 3 h and the annealed sample containing 4 mol% ZrO2 has the lowest content of crystalline phases, which is consistent with the results of crystallization kinetics analysis. The obtained conclusions offer some useful information to understand the role of ZrO2 in iron sodium phosphate glasses for nuclear waste immobilization and the thermal stability of the waste forms containing zirconium.

Millimeter-scale Al2O3 ceramic hollow spheres have been successfully prepared by an improved emulsion microencapsulation method. That is: Firstly, stable oil-in-water emulsion droplets, using alumina sol as continuous phases (water phase) and dimethicone as dispersion phase (oil phase), are prepared in advance by using self-made T-shape micro-emulsion channel as an emulsion droplet generator. Then, the prepared droplets suffer rotating process for 12 h at 100 °C in a rotary evaporator, and Al2O3 gel hollow spheres are produced. Finally, Al2O3 ceramic hollow spheres with wall thickness of 30~100 μm and diameter of 600~2500 μm are successfully prepared through calcining the produced gel hollow spheres at 1200 °C for 4 h. The main crystalline of the prepared Al2O3 ceramic hollow spheres is α-Al2O3. This method provides a novel synthesizing method for preparing millimeter-scale ceramic hollow spheres which have great potential application in Inertial Confined Fusion (ICF) required hollow pellet.

•The increase in TiO2 content strengthen phosphate network chains.•TiO2 link to phosphate unit through POTi bonds.•Q0 formed at expense of Q1 and Q2 increase with increment of TiO2 content.Structure and thermal properties of xTiO2·(90 − x) (60P2O5–40Fe2O3)⋅10CaF2 (x = 0, 5, 10, 15, 20 and 25 mol%) glasses are investigated in detail by Fourier Transform Infrared Spectrum (FTIR) and Differential Thermal Analysis (DTA), respectively. It is found that incorporation of TiO2 increase the density and glass transition temperature of iron phosphate system glass. The increment of doped-TiO2 can also strengthen phosphate network chains due to increasing O/P ratios and more orthophosphate (Q0) units formed in the glass structure at expense of pyrophosphate (Q1) units and metaphosphate (Q2) groups. Moreover, the structure of iron phosphate glass with TiO2 content contain distorted octahedral [TiO6] linked to phosphate unit through POTi bonds, thus enhanced structure cohesion and increased density obtained. The knowledge provides an improved understanding of the role of TiO2 in the structure of iron phosphate glasses.

•The IBP glass containing 18 mol% of CeO2 has immiscible solid in appearance.•Monazite CePO4 appears in IBP glass with CeO2 content more than 9 mol%.•The IBP glass with 18 mol% CeO2 content contains both CePO4 and FePO4 crystal.•xCeO2–(100 − x)(36Fe2O3–10B2O3–54P2O5) glass forming region is from x = 0 to x = 9, mol%.•The IBP glass with up to 15 mol% CeO2 not produces fundamental glass networks' change.Glasses with compositions xCeO2–(100 − x)(36Fe2O3–10B2O3–54P2O5) (x = 0, 3, 6, 9, 12, 15 and 18, mol%) are prepared by conventional melt quench method. Glass formation and structure of CeO2-doped iron borophosphate glass have been investigated by using X-ray diffraction and FTIR spectroscopy. The results show that the samples doped with less than 9 mol% CeO2 are fully amorphous, crystallization occurs when the content of CeO2 reaches 9 mol%, and the main crystal phase, monazite CePO4, is embedded in an amorphous matrix. When doped CeO2 reaches 18 mol%, another crystal phase, FePO4, also crystallizes from the structure of the formed glass matrix, and immiscible solid formed in its appearance. IR data indicate that the studied glass structure consists predominantly of orthophosphate (Q0) units, pyrophosphate (Q1) units and [BO4] units. The glass transition temperature (Tg) is improved by doping with CeO2, which suggests that Ce acts a role of strengthening the cross-links between the borophosphate chains of the glasses.

•Partial crystallization occurs for the IBP glass containing more than 6 mol% La2O3.•DR values of the La2O3 doped IBP glasses are about 10−9 g cm−2 min−1.•La2O3 and the formed LaPO4 crystal insignificantly affect the DR of the IBP glass.•Tg increases with the addition of La2O3 in the glass formation range.•IBP glasses are potential hosts for the immobilization of La-rich HLWs.Glass forming ability, structure and properties of La2O3 containing iron borophosphate compounds have been studied by XRD, SEM, FTIR, DTA, Raman spectroscopy and aqueous dissolution rate. The results show that the 36Fe2O3–10B2O3–54P2O5 glass with 3 mol% La2O3 is homogeneously amorphous. Partial crystallization occurs for the glass containing up to 6 mol% La2O3 and the insoluble lanthanum is mainly concentrated in the formed crystalline LaPO4. The structure of the samples is mainly based on pyrophosphate, orthophosphate and [BO4] units, and becomes more depolymerized with addition of La2O3. Moreover, Tg values increase with La2O3 content in the glass forming range. The dissolution rates of the studied glasses are about 10−9 g cm−2 min−1, demonstrating that the studied glasses and glass-ceramics posses high aqueous chemical durability. The doped La2O3 and the formed LaPO4 crystal insignificantly affect the dissolution rates of the base glass. The conclusions indicate that the studied iron borophosphate glasses are potential hosts for the disposal of high-level nuclear wastes which are rich in lanthanum.

•Millimeter-scale Al2O3 hollow spheres are prepared by template synthesis method.•The mechanisms of Al2O3 hollow sphere formation are revealed.•The laser transmittance of Al2O3 hollow spheres are improved by MgO-doping.Translucent MgO-doped Al2O3 hollow spheres with millimeter-scale in diameter were prepared by a three-sintering-step method using polystyrene (PS) spheres as template through connection function of chitosan-assistant aggregation. The as-prepared hollow spheres were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscope (FE-SEM) and Electron Probe Microanalysis (EPMA). The results show that the obtained translucent MgO-doped Al2O3 hollow spheres has diameter of 1–2 mm, wall thickness of 130 μm and 532 nm pulse laser transmittance of 50%. It is also noted that the formation of PS–Al2O3 core–shell spheres is based on the connection function of –OH and –NH2 groups in chitosan molecules. This method provides a synthesizing method for preparing translucent millimeter-scale hollow spheres which have a great potential application for Inertial Confined Fusion (ICF) required hollow pellet.

•IBP glass with less than 6 mol% Zr mainly crystallize Fe4(PO4)2O, Fe2(PO4)O at 850 °C.•ZrP2O7 appears when IBP glass doped with more than 6 mol% ZrO2.•ZrO2 restrains Fe4(PO4)2O, Fe2(PO4)O crystallized from the ZrO2-doped IBP glasses.•PO3− and PO43− groups gradually transform into P2O74− groups with ZrO2 increasing.The crystallization and structure of ZrO2-doped 36Fe2O3–10B2O3–54P2O5 glasses and crystalline compounds are studied by using X-ray diffraction and FTIR spectroscopy, respectively. It is found that the main crystallization is Fe4(PO4)2O, Fe2(PO4)O when 36Fe2O3–10B2O3–54P2O5 glass with less than 6 mol% of ZrO2 is heated at 850 °C. When the doped ZrO2 is larger than 6 mol% (including 6 mol%), ZrP2O7 crystallization appear. Furthermore, their crystallization behaviors suggest that ZrO2 can promote ZrP2O7 crystallized from the ZrO2-doped 36Fe2O3–10B2O3–54P2O5 glass and restrain Fe4(PO4)2O and Fe2(PO4)O crystallization formed due to the PO3− groups and PO43− phosphate groups gradually transforming into pyrophosphate P2O74− groups with increasing content of ZrO2. The knowledge provides an improved understanding of the role of Zr in the structure of iron borophosphate glasses and its crystalline compounds.