The effect of HNO3 on morphology, phase transformation, and luminescence properties of LaPO4:Eu3+ phosphors

• LaPO4:Eu3+ with different morphologies were prepared by adjusting the amount of HNO3.
• Catalyst, surfactant, or template were not used.
• The effect of HNO3 on optical properties and structural stability were investigated in detail.

LaPO4:Eu3+ powders with different morphologies were hydrothermally constructed by adjusting the amount of HNO3 without using a catalyst, surfactant, or template. The as-prepared products were characterized by photoluminescence spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution-transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), infrared (IR) spectra, and X-ray photoelectron spectroscopy. The SEM study revealed that the amount of HNO3 played a crucial role in the morphology of the final products. The XRD results indicated that the as-prepared samples were in the monoclinic phase when 3 mL of HNO3 was used. The HR-TEM micrographs and SAED results demonstrated that the prepared nanorods were single and crystalline in nature with HNO3, and that they grew preferentially along the [0 1 2] direction. The emission spectra showed that the LaPO4:Eu3+ samples had the strongest emission intensity when prepared with HNO3.