## 1 Introduction  
Recent developments in new functional materials, with the help of theoretical simulations and data science, could accelerate practical applications of these new functional materials. For progressing those practical applications, not only improved and effective material processing methods, but also quick feedback of the evaluated results of the structure, composition, and chemical state of new products are necessary. Dedicated transmission electron microscope (TEM) is a powerful candidate for evaluating the structure and chemical characteristics of materials, with a nanometer-scale spatial resolution [1; 2; 3; 4]. However, it is a destructive inspection process due to a necessity of thin specimens of about tens of nanometers for transmission experiments. For a nondestructive inspection process with a high spatial resolution, evaluations based on scanning electron microscopy are useful. A soft X-ray emission spectroscopy (SXES) instrument, combined with a scanning electron microscope (SEM) and/or an electron probe microanalyzer (EPMA) can realize a nondestructive inspection process of the chemical state of materials, with a spatial resolution of about 1 \(\upmu\)m or better [5; 6; 7]. If this occurs, SXES microscopy can make a quick feedback loop of the evaluated results of new products for materials processing.  
The chemical state analysis of boron is a topical issue in materials science. Boron forms four allotropes of \(\alpha\),\(\beta\)-mombohedral boron and \(\alpha\),\(\beta\)-tetragonal boron. These materials have a three-dimensional network of boron clusters. \(\alpha\)-rhombohedral boron is expected to be a superconductor by electron doping [8; 9]. Boron compounds also express interesting characteristics as metals, semiconductors, insulators, and superconductors [10; 11; 12]. In addition,boron is one of the key chemical species as a fine additive element in the production of functional tuff steel, magnetic materials, the formation of fundamental switches for large integrated circuits, medical applications, etc. [13; 14; 15; 16]  
The alkaline-earth hexaborides CaB\({}_{6}\), SrB\({}_{6}\), and BaB\({}_{6}\) are candidate materials for thermoelectric conversion because of their large Seebeck coefficients and electrical conductivities [17; 18]. Each material is composed of a three-dimensional network of B\({}_{6}\) octagonal clusters, placed at each corner of a cubic unit cell, and an incorporated alkaline-earth metal atom at the body-center position of the unit cell. The metal atom can transfer two valence electrons to the B\({}_{6}\) cluster network, resulting in an \(n\)-type semiconductor. For realizing a thermoelectric device using B\({}_{6}\) cluster network materials, a \(p\)-type semiconductor is necessary. As Na atoms only have one valence electron, Na substitution to the Ca site of CaB\({}_{6}\) (Na-doped CaB\({}_{6}\)) is a hole-doping to the B\({}_{6}\) cluster network, causing a \(p\)-type semiconductor as a bulk [19]. This \(p\)-type Na-doped CaB\({}_{6}\) was evaluated by using a commercial SXES-EPMA instrument, which reported an inhomogeneous charge distribution due to a compositional fluctuation in the bulk [20]. \(p\)/\(n\)-type controlled CaB\({}_{6}\) bulk materials, prepared by the molten-salt method with starting materials containing different compositional ratios of Ca and B, were also examined by SXES-EPMA. It was revealed that the produced \(p\)-type bulk CaB\({}_{6}\) specimen included locally \(n\)-type regions [21].  
In this report, nondestructive chemical state evaluations of \(p\)/\(n\)-controlled SrB\({}_{6}\) bulk specimens are presented. Two-dimensional spectral mapping of the soft X-ray emission spectra of these materials gives information of elemental inhomogeneity, and the related hole-doping nature appears as a chemical shift in the spectra of the material.