What is F centered?
An F center or Farbe center (from the original German Farbzentrum, where Farbe means color and zentrum means center) is a type of crystallographic defect in which an anionic vacancy in a crystal lattice is occupied by one or more unpaired electrons.
What are F-centres in solid state?
Answer: The anionic sites occupied by unpaired electrons are called F-centres. Such defects also impart colour to the crystals. The colour results by excitation of these electrons when they absorb energy from the visible light falling on the crystals.
What are F-centres examples?
F-centres: When the anionic sites of a crystal are occupied by unpaired electrons, the ionic sites are called F-centres. These unpaired electrons impart colour to the crystals. For example, when crystals of NaCl are heated in an atmosphere of sodium vapour, the sodium atoms are deposited on the surface of the crystal.
What is F-centre and what is its use?
F-centres – This is type of defect and called metal excess defect. These type of defects seen because of missing of anions from regular site leaving a hole which is occupied by electron to maintain the neutrality of the compound.
What are F-centres for Class 12?
The electron occupying holes, created by missing of anions from the lattice sites are called F-centres. These F-centres are responsible for colour of compound.
What are F-centres mention the consequences of F-centres?
The anionic sites occupied by unpaired electrons are called F-centres. Such defects also impart colour to the crystals. The colour results from the excitation of these electrons when they absorb energy from the visible light falling on the crystals. F centre is a type of crystallographic defect.
What are the F-centers how they are formed?
The F-centers are point defects and can be readily formed in alkaline halides with the aid of a source of ionizing radiation, such as a Tesla coil or X-ray source. Apparently the ionizing radiation causes the loss of electrons from halide ions. An electron then becomes trapped in the halide ion vacancy.
What is true for F-centre?
The electron of the potassium atom that is ionized in the KCl matrix is trapped by the chloride ion vacancy. This trapped electron can be freed into the crystal by absorbing visible light and hence, the colour. A trapped electron at an anion vacancy is an electronic defect and it is known as F-centre.
What are F-centres Ncert?
What is F-centres how is it formed?
An F-center, Farbe center or color center (from the original German Farbzentrum; Farbe means color, and zentrum center) is a type of crystallographic defect in which an anionic vacancy in a crystal is filled by one or more unpaired electrons. Cl− vacancies are generated, because of the excess of Na+.
What do you mean by F-centre write one property which is caused due to the presence of F-centre in a solid?
The colours and paramagnetic behaviour of the solid is due to the presence of F-center in a solid.