- Volumes 84-95 (2024)
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Volumes 72-83 (2023)
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Volume 83
Pages 1-258 (December 2023)
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Volume 82
Pages 1-204 (November 2023)
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Volume 81
Pages 1-188 (October 2023)
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Volume 80
Pages 1-202 (September 2023)
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Volume 79
Pages 1-172 (August 2023)
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Volume 78
Pages 1-146 (July 2023)
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Volume 77
Pages 1-152 (June 2023)
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Volume 76
Pages 1-176 (May 2023)
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Volume 75
Pages 1-228 (April 2023)
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Volume 74
Pages 1-200 (March 2023)
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Volume 73
Pages 1-138 (February 2023)
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Volume 72
Pages 1-144 (January 2023)
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Volume 83
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Volumes 60-71 (2022)
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Volume 71
Pages 1-108 (December 2022)
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Volume 70
Pages 1-106 (November 2022)
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Volume 69
Pages 1-122 (October 2022)
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Volume 68
Pages 1-124 (September 2022)
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Volume 67
Pages 1-102 (August 2022)
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Volume 66
Pages 1-112 (July 2022)
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Volume 65
Pages 1-138 (June 2022)
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Volume 64
Pages 1-186 (May 2022)
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Volume 63
Pages 1-124 (April 2022)
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Volume 62
Pages 1-104 (March 2022)
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Volume 61
Pages 1-120 (February 2022)
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Volume 60
Pages 1-124 (January 2022)
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Volume 71
- Volumes 54-59 (2021)
- Volumes 48-53 (2020)
- Volumes 42-47 (2019)
- Volumes 36-41 (2018)
- Volumes 30-35 (2017)
- Volumes 24-29 (2016)
- Volumes 18-23 (2015)
- Volumes 12-17 (2014)
- Volume 11 (2013)
- Volume 10 (2012)
- Volume 9 (2011)
- Volume 8 (2010)
- Volume 7 (2009)
- Volume 6 (2008)
- Volume 5 (2007)
- Volume 4 (2006)
- Volume 3 (2005)
- Volume 2 (2004)
- Volume 1 (2003)
The microstructural changes taking place during heating of calcium orthophosphate (Ca3(PO4)2) agglomerates were examined in this study. The starting powder was prepared by the spray-pyrolysis of calcium phosphate (Ca/P ratio=1.50) solution containing 1.8 mol·L−1 Ca(NO3)2, 1.2 mol·L−1 (NH4)2HPO4 and concentrated HNO3 at 600 °C, using an air-liquid nozzle. The spray-pyrolyzed powder was found to be composed of dense spherical agglomerates with a mean diameter of 1.3 μm. This powder was further heat-treated at a temperature between 800 and 1400 °C for 10 min. When the spray-pyrolyzed powder was heated up to 900 °C, only β-Ca3(PO4)2 was detected, and the mean pore size of the spherical agglomerates increased via the (i) elimination of residual water and nitrates, (ii) rearrangement of primary particles within the agglomerates, (iii) coalescence of small pores (below 0.1 μm), and (iv) coalescence of agglomerates with diameters below 1 μm into the larger agglomerates. Among the heat-treated powders, pore sizes within the spherical agglomerates were observed to be the largest (mean diameter: 1.8 μm) for the powder heat-treated at 900 °C for 10 min. With an increase in heat-treatment temperature up to 1000 °C, the spherical agglomerates were composed of dense shells. Upon further heating up to 1400 °C, the hollow spherical agglomerates collapsed as a result of sintering via the phase transformation from β- to α-Ca3(PO4)2 (1150 °C), thus leading to the formation of a three-dimensional porous network.