Fluence-Dependent Multimodal Response of NdGaO₃(110) Single Crystals to 147 MeV Kr Ions

This exploratory study compares one pristine NdGaO3(110) crystal with one crystal irradiated at 1 × 1011 ions cm−2 and one crystal irradiated at 1 × 1012 ions cm−2 using 147 MeV 84Kr ions. Because each condition is represented by a single independent specimen, specimen-to-specimen variability is confounded with the irradiation condition, and no specimen-level statistical inference is made. Symmetric X-ray diffraction, condition-averaged confocal micro-Raman spectroscopy, and UV–Vis–NIR transmission were used to compare surface-normal lattice response, local vibrational line shapes, and radiation-induced optical attenuation. The nearly angle-independent XRD shift at 1 × 1011 ions cm−2 is dominated by a common angular offset, whereas the two surviving harmonics at 1 × 1012 ions cm−2 give a model-conditioned estimate ε110 = +0.509 ± 0.040%. At the higher fluence, the integrated intensities captured in the coupled θ–2θ condition decrease to 9.35 ± 0.46% for (110) and 1.29 ± 0.06% for (220), while the (220) FWHM ratio reaches 7.83 ± 0.73. These fit-derived errors do not include specimen alignment or between-specimen variability. The archived condition-averaged Raman spectra retain Pbnm-like vibrational groups, while the fitted FWHM values of the 168, 214/215, and 449–470 cm−1 features increase by 15.7%, 19.4%, and 14.8%. The bulk-integrated Nd3+ 4f–4f maxima remain stable within the wavelength sampling, whereas the effective Rp-normalized differential attenuation at 275–285 nm reaches 388.7 cm−1. The data support an exploratory description of a strained and diffraction-heterogeneous crystalline layer; complete amorphization, quantitative mosaicity, a damage threshold, track dimensions, and a microscopic defect identity are not established.