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Fluoride (F) distributions in a synthesized hydroxyl apatite (HAp) block of uniform structure and in teeth were measured using in-air micro-PIGE (particle induced gamma-ray emission) and micro-PIXE system, which was developed at the Japan Atomic Energy Agency (JAEA) in Takasaki. We used a nuclear reaction ¹⁹F(p,αγ)¹⁶O to measure F density. The characteristic important feature of this technique is that it can measure F quantitatively in a microscopic area of the specimen placed in air. A surface of the HAp, the enamel buccal surface of a human molar, and a class V cavity wall in dentin were applied a sodium fluoride solution (NaF) four times and immersed in a normal saline solution. After one month, specimens were cut longitudinally. The F distributions were measured from the surface toward the inner part of the cut surface. The F penetration into specimens following NaF application was quantitatively configured in a two-dimensional mapping form. This method is quite useful for characterizing F distribution in a microscopic area of a tooth.

For confirming the feasibility of micrometer scale analysis of lithium distribution in the all-solid-state lithium battery using a sulfide-based solid electrolyte, the cross-section of pellet type battery was analyzed by microbeam particle-induced X-ray emission (PIXE) and particle-induced gamma-ray emission (PIGE) measurements. A three-layered pellet-type battery (cathode: LiNbO₃-coated ${\mathrm{\text{LiCoO}}}_2+{\mathrm{\text{Li}}}_{10}{\mathrm{\text{GeP}}}_2{\mathrm{\text{S}}}_{12}$/solid electrolyte: ${\mathrm{\text{Li}}}_{10}{\mathrm{\text{GeP}}}_2{\mathrm{\text{S}}}_{12}$/anode: ${\mathrm{\text{TiS}}}_2+{\mathrm{\text{Li}}}_{10}{\mathrm{\text{GeP}}}_2{\mathrm{\text{S}}}_{12}$) was prepared for the measurements. Via elemental mapping of the cross-section of the prepared battery, the difference in the yields of gamma rays from the ${}^7\mathrm{\text{Li}}{(p,p^{\prime }\gamma )}^7\mathrm{\text{Li}}$ inelastic scattering (i.e., the lithium concentrations) between the composite electrodes and the solid electrolyte layer was clarified. The difference in the number of lithium ions at the composite anode/solid electrolyte interface of ($\mathrm{\Delta }n=0.26\times 10^{-4}$ mol) in the battery can be clearly detected by the microbeam PIGE technique. Therefore, lithium distribution analysis with a micrometer-scale spatial resolution is demonstrated. Further analysis of the cathode/anode composite electrodes with the different states of charge could provide important information to design a composite for high-performance all-solid-state lithium batteries.