Journal of the Ceramic Society of Japan
vol. 134, no.2, 2026

◆Full papers◆

Preparation and thermal expansion behavior of an EDI-type SAPO with dehydration-induced negative thermal expansionpdf

https://doi.org/10.2109/jcersj2.25144

Daiki Nagai, Haruna Igawa, Naoki Arimitsu, Yasuhide Mochizuki, Akira Nakajima and Toshihiro Isobe

51

This study investigates the thermal stability and thermal expansion behavior of K-EDI-type SAPO and ion-exchanged EDI-type SAPO. K-EDI-SAPO was synthesized and subsequently subjected to ion exchange using various chloride solutions. ICP-OES analysis confirmed that the framework composition (Si, Al, P) remained unchanged, indicating that only pore cations were replaced. Monovalent ions were almost completely exchanged, except Li+ (∼76 %), while divalent Ca2+ and Mg2+ showed lower rates (∼80 and 45 %, respectively). XRD patterns revealed successful synthesis of single-phase K-EDI-SAPO, with peak shifts after ion exchange reflecting changes in the lattice parameters. Rb-exchange slightly increased lattice volume, whereas Ca2+ exchange reduced crystallinity. Thermal expansion studies showed giant negative thermal expansion (NTE) for K-EDI-SAPO (−342 ppm/K) and significant NTE for Rb-EDI-SAPO (−99 ppm/K). Other ion-exchanged samples collapsed upon heating, attributed to stronger Coulombic interactions between small or divalent cations and framework oxygen. TG analysis linked dehydration behavior to lattice contraction, demonstrating that Rb substitution broadens the NTE temperature window.

Thermal expansion property of sintered polycrystals and unit cell of celsian solid solution (Ba,Sr)Al2Si2O8pdf

https://doi.org/10.2109/jcersj2.25120

Yuichi Kobayashi, Masatomo Hattori, Masato Inoue and Yorikazu Murabayashi

57

The purpose of this work is to clarify the transformation mechanism from hexacelsian to celsian and the thermal expansion properties of celsian solid solutions (Ba1−xSrxAl2Si2O8, x = 0–1.0) using high-temperature powder X-ray diffraction and dilatometry of sintered polycrystals. Hexacelsian polycrystals were prepared from BaCO3, SrCO3 and finely purified kaolin powder (Al2O3·2SiO2·2H2O) by heat-treatment at 950–1400 °C. Sr-hexacelsian polycrystals transformed to celsian via nucleation and growth from inner to surface to develop cracks at surface at 1100–1200 °C. Single phase of celsian polycrystals in composition of Ba1−xSrxAl2Si2O8 (x = 0–0.8) were prepared by heat-treatment at 1400 °C for 1 h and their dilatometric thermal expansion coefficient (TEC) were almost 4.0–4.2 × 10−6/°C from 25 to 900 °C. On the other hand, average TEC of unit cell of celsian measured by high temperature X-ray diffraction were lower than the values of dilatometry and increased from 3.0 × 10−6/°C to 3.8 × 10−6/°C with the Sr content.

Highly water vapor-durable solid electrolyte type ammonia gas sensor with ammonium rare earth niobate as an auxiliary sensing electrodepdf

https://doi.org/10.2109/jcersj2.25114

Shinji Tamura, Ryo Yamashita and Nobuhito Imanaka

64

A solid electrolyte-type ammonia (NH3) gas sensor with high durability for water vapor was devised by combining a trivalent Al3+ ion-conducting solid electrolyte and ammonium lanthanum niobate (NH4LaNb2O7). The present sensor, using NH4LaNb2O7 as the auxiliary sensing electrode, detected NH3 gas concentration by obeying the theoretical Nernst relationship even at 180 °C. The present sensor exhibited a quantitative response to NH3 gas concentration change without the influence of water vapor even in a highly humid atmosphere containing 4.2 vol % H2O for over 3 months, indicating that the sensor with the NH4LaNb2O7 auxiliary sensing electrode was revealed to possess an extraordinarily high water vapor durability.

Li6.5La3Zr1.5−xBi0.2Sb0.3SnxO12 as a novel solid electrolyte for sintered-type solid-state batteriespdf

https://doi.org/10.2109/jcersj2.25152

Zongqi He, Ken Watanabe, Koichi Suematsu and Kengo Shimanoe

71

Sintered-type solid-state batteries (SSSBs) based on Li-ion-conductive oxides have attracted attention as the next generation of batteries, offering long lifetimes, high safety, and high energy density. The cubic garnet-type Li7La3Zr2O12 (LLZ) is a promising candidate for electrolyte materials of SSSBs. Its densification temperature is crucial for achieving SSSBs, as excessively high sintering temperatures lead to the formation of undesirable interphases between LLZ and electrode materials. This study reports new Li6.5La3Zr1.5−xBi0.2Sb0.3SnxO12 electrolytes with high sintering ability and high compatibility with metallic Li. The Sn substitution enhances sintering property, resulting in a lower densification temperature. On the other hand, the stability against Li metal decreases sharply as the Sn substitution level increases. Finally, Li6.5La3Zr1.5Bi0.2Sb0.3O12 and Li6.5La3Zr1.3Bi0.2Sb0.3Sn0.2O12 exhibit good sinterability and high wettability and compatibility with Li metal, with a high Li-ion conductivity of 4.0 × 10−4 and 6.3 × 10−4 S/cm at 25 °C, respectively.

◆Notes◆

Layered proton-type zirconium phosphates as candidate heat storage materials based on water intercalationpdf

https://doi.org/10.2109/jcersj2.25134

Susumu Nakayama

77

Utilization of waste heat is essential for energy conservation and CO2 reduction, driving demand for the development of efficient thermal storage materials. Although various types of thermal storage materials have been proposed, few meet the requirements of reversibility, high energy density, long life, and ease of handling. This study reports that α-Zr(HPO4)2·H2O and γ-Zr(PO4)(H2PO4)·2H2O, which possesses a layered structure with one and two interlayer water molecules, exhibits water intercalation at temperatures below 160 and 80 °C and is an excellent candidate for heat storage applications. The apparent activation energy for interlayer water desorption was 91 kJ·mol−1 for both samples. TG and DSC measurements revealed an endothermic reaction during heating, corresponding to the weight loss from desorption of water molecules, and an exothermic reaction during cooling, corresponding to the weight gain from insertion of water molecules. α-Zr(HPO4)2·H2O and γ-Zr(PO4)(H2PO4)·2H2O also demonstrated excellent cycling performance, with calorific values obtained from the endothermic and exothermic peak areas in the third cycle of −147 and 203 J·g−1, and −82 and 121 J·g−1, respectively. These findings highlight the potential of α-Zr(HPO4)2·H2O and γ-Zr(PO4)(H2PO4)·2H2O as sustainable heat storage materials for energy conservation and thermal management applications.

Antimicrobial and antiviral activity of proton-type zirconium phosphatepdf

https://doi.org/10.2109/jcersj2.25123

Susumu Nakayama

82

Antibacterial and antiviral inorganic materials are attracting increasing attention for their biomedical and environmental applications. This study aimed to examine the antibacterial and antiviral properties of zirconium phosphate powders, Zr(HPO4)2·H2O, Zr(PO4)(H2PO4)·2H2O, HZr2(PO4)3, and (H3O)Zr2(PO4)3, and to clarify the role of pH in their activity. Antibacterial activity against Escherichia coli was confirmed in Zr(PO4)(H2PO4)·2H2O, HZr2(PO4)3, and (H3O)Zr2(PO4)3 powders; high antiviral activity against the bacteriophage Qβ was detected in Zr(PO4)(H2PO4)·2H2O and (H3O)Zr2(PO4)3 powders, with the antiviral activity of Zr(PO4)(H2PO4)·2H2O being superior to that of (H3O)Zr2(PO4)3. After immersion in deionized water for 1 d, the pH values of the Zr(PO4)(H2PO4)·2H2O, HZr2(PO4)3, and (H3O)Zr2(PO4)3 powders reduced to 3.64, 4.41, and 3.99, respectively, becoming lower than that of Zr(HPO4)2·H2O (5.12). The observed effects were attributed to the lower pH caused by the formation of H3O+ upon contact with water. These results demonstrate that acidity is crucial in the antibacterial and antiviral functions of zirconium phosphate-based materials, providing insights for the design of functional inorganic antimicrobial agents.

◆Announcement◆

Call for a Guest Editor for the Featurepdf

https://doi.org/10.2109/jcersj2.134.A2-1

A2-1


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