What is the principle that phosphor gives off light ?

One, “phosphors” luminous enlightenment
In order to find out the chemical composition of phosphor powder, we first thought about the luminescence of fireflies. The luminescence principle of fireflies mainly has the following series of processes.
Photoforming protein + photoforming enzyme containing oxygenated photoforming protein (emitting green light)
Oxygen-containing photogenic protein +H2O photogenic protein
That’s why fireflies glow continuously, with flashes of light. It’s worth noting that the green light emitted by fireflies is a “cold light” with a conversion rate of 97%.
Secondly, we also pay attention to the luminescence of luminescent plastics. Luminescent plastics mainly mix some radioactive substances into ordinary plastics, such as 14C, 35Sr, 90Sr, Na, Th, and luminescent materials ZnS and CaS. These sulfides are excited by the irradiation of radiation light and emit visible light (cold light).
The chemical composition of phosphor powder is finally deepened to the standard chemical formula by fuzzy silicate, tungstate, single elements Ba and Sr. The chemical composition is as follows:
category
Chemical formula
color
Dense degree of
Red powder
Y2O3: Eu
white
5.1 + / – 0.2
Green powder
CeMgL11O19: Tb
white
4.2 + / – 0.2
Blue powder
BaMgAl10O17: Eu
white
3.7 + / – 0.2
Bimodal blue powder
BaMgA10O17 :(Eu, Mn)
white
3.8 + / – 0.2
Up-conversion phosphor powder, namely, the composition of infrared excitation phosphor powder is:
Chemical composition: YErYbF3
Exterior view: white inorganic powder
Grain size: 30nm
Excitation wavelength: 980nm
Luminous color: green light
Characteristics: high light transmittance, high solvent resistance, acid and alkali resistance
Several methods to deal with the harm of phosphor powder
As phosphors contain a large amount of Hg in the process of filling solar lamp tubes, the main source of their harm is the Hg vapor emitted by them. The authoritative data show that:
Mercury vapor up to 0.04 to 3 mg, can make people in 2 to 3 months of chronic poisoning; Up to 1.2 to 8.5 milligrams can cause acute mercury poisoning, and up to 20 milligrams can directly cause animal death.
Mercury once in the body, can quickly diffuse, and accumulated to the kidney, breast and other tissues and organs of chronic mercury poisoning can lead to mental disorders, plant nerve disorder, acute symptoms often have a headache, fatigue, fever, oral cavity and digestive tract swelling sore gums, player bleeding, loose teeth, etc., part of the skin red spot, pimples, a small number of renal damage, individual kidney pain, chest pain, dyspnea, purple purple acute interstitial pneumonia, etc.
Mercury, if improperly kept and disposed of, will also cause great harm to the ecological environment. It enters the environment in various forms, directly pollutes soil, air and water, and then enters the human body through the food chain, endangering people’s healthy life. Therefore, it is absolutely not allowed to throw away the fragments of solar lamp tubes everywhere.
If indoor daylight lamp tube is broken, can use iodine 1 gram/cubic meter to add alcohol hind fumigation or use 1 gram/cubic meter iodine to disperse directly in the ground 8-12 hours, the iodine that volatilizes or sublimate and the mercury in the air produce the mercury iodide that volatilizes hard (Hg+I2 = HgI2). To reduce the concentration of mercury vapor, 5-10% ferric chloride or 10% bleach can be used to wash the contaminated ground.
The phenomenon of material luminescence can be roughly divided into two categories: one is that the material is heated and generates heat radiation and luminescence; the other is that the object is excited and absorbs energy and transitions to the excited state (non-stable state), and emits energy in the form of light in the process of returning to the ground state. Luminescent materials with rare earth compounds as the matrix and rare earth elements as activators mostly belong to the latter category, that is, rare earth phosphors. Rare earth element atoms have abundant electronic energy levels, because of the existence of 4f orbital in the electron configuration of rare earth element atoms, which creates conditions for a variety of energy level transitions and thus obtains a variety of luminous properties. Rare earth is a great treasure house of luminescent materials. Among all kinds of luminescent materials developed by human beings, rare earth elements play a very important role.
  since 1973, the world energy crisis, countries are committed to developing energy-saving light-emitting materials, so the use of rare earth tricolor fluorescent materials fluorescent research arises at the historic moment. In 1979, philips was the first company in the Netherlands to develop a successful, then put on the market, since then, a variety of specifications of rare earth three-color fluorescent lamps have been published. With the continuous improvement of human living standard, color TV sets have begun to develop towards large screen and high definition. Rare earth phosphors show their superior performance in these aspects, thus providing an ideal luminous material for the realization of large screen and high definition of color TV sets.
Therefore, rare earth fluorescent materials have been used more and more widely in recent years, and the annual consumption has increased rapidly.
according to different excitation source, the rare earth luminescent material can be divided into (trigger) ultraviolet or visible photoluminescence, cathode ray emitting (in electron beam excitation), X-ray emitting (trigger) X ray and electroluminescent (trigger) electric field materials, etc.
Cathode ray luminescent material – phosphors for display
Mainly used in television, oscilloscope, radar and computer and other types of fluorescent screen and display. Rare earth red phosphors (Y2O3: Eu and Y2O2S: Eu) are used in the fluorescent screen of color TV sets, so that the brightness of color TV sets reaches a higher level. Blue and green phosphors still use non-rare earth phosphors, but La2O2S: Tb green phosphors have better luminescence characteristics and promising development prospects. Recently, EBU (European broadcasting union) color and Y2O2S: Eu are used in color TV sets. Unlike TV sets, which attach less importance to the reproducibility of color and give priority to brightness, computers use orange and stronger red. The content of Eu in Y2O2S is usually 5-7wt %. And the content of Eu in the red powder of color TV sets is about 1.5 times that of computers.