Influence of hot isostatic pressing on sintering trajectory and optical properties of transparent Nd:YAG ceramics

•Transparent Nd:YAG ceramics manufactured by HIP sintering technology.•The microstructural evolution during sintering can be better controlled by HIP compared to natural vacuum sintering technology.•Grain size can be limited to less than 2μm even for highly transparent ceramics with full density (i.e., >99.9%).•Intragranular porosity formation at the final stage of sintering can be avoided thanks to HIP technology.•As-obtained ceramics present high optical transmittance and high laser efficiency.