Question

An example of a ferromagnetic oxide is (a) \(\mathrm{TiO}_{2}\) (b) \(\mathrm{CrO}_{2}\) (c) \(\mathrm{Mn}_{2}^{2} \mathrm{O}_{7}\) (d) \(\mathrm{Fe}_{3} \mathrm{O}_{4}^{2}\)

Short answer

The ferromagnetic oxide is (b) \(\mathrm{CrO}_{2}\).

Step-by-step solution

Understanding Ferromagnetism

Ferromagnetism is a property that allows certain materials to become magnets when exposed to a magnetic field. Common ferromagnetic elements include iron (Fe), cobalt (Co), and nickel (Ni), and some of their compounds exhibit this property.

Analyzing the Options

We need to determine which of the given options is a ferromagnetic oxide. The options are: (a) \(\mathrm{TiO}_{2}\) – titanium dioxide, generally not ferromagnetic. (b) \(\mathrm{CrO}_{2}\) – chromium dioxide, known to be ferromagnetic. (c) \(\mathrm{Mn}_{2}^{2} \mathrm{O}_{7}\) – this is a typo and should be reviewed for accuracy; generally, manganese oxides are not ferromagnetic. (d) \(\mathrm{Fe}_{3} \mathrm{O}_{4}\) – magnetite, which is a well-known ferromagnetic oxide.

Identifying the Correct Answer

From the analysis, we know that \(\mathrm{CrO}_{2}\) and \(\mathrm{Fe}_{3} \mathrm{O}_{4}\) are both known ferromagnetic oxides. However, \(\mathrm{CrO}_{2}\) is specifically highlighted for its application in recording media due to its strong ferromagnetic properties.

Key concepts

Ferromagnetic Oxides

Ferromagnetic oxides are fascinating compounds that can display magnetic properties due to the alignment of their atomic moments. In nature, there are several oxide materials known for their ferromagnetic abilities.

- **Magnetite (Fe_3O_4)**: This is one of the most well-known ferromagnetic oxides. It is naturally occurring and has been used throughout history as a magnetic material. The iron atoms in the structure of magnetite align themselves under a magnetic field, contributing to its ferromagnetic property.
- **Chromium Dioxide (CrO_2)**: This synthetic compound is another excellent example and is popular in applications that require recording media due to its inherent ferromagnetism.

The distinct alignment of the electronic spins in such oxides is responsible for their magnetic behavior, making them useful in various modern technologies.

Magnetic Properties of Materials

The magnetic properties of any material are largely determined by the alignment of its atomic and subatomic particles. This principle is central to understanding materials like ferromagnetic oxides. Ferromagnetism is one type of magnetism, and it is characterized by:

- **Magnetization**: The ability of a material to become magnetized. - **Curie Temperature**: Above this temperature, the ferromagnetic material loses its magnetic properties because the thermal energy disrupts the alignment of atomic spins.
- **Magnetic Domains**: Regions within the material where the magnetic moments are aligned. In the absence of an external magnetic field, these domains are oriented randomly. When an external field is applied, these domains can align in one direction, causing the material to become magnetized.

These properties are pivotal in designing and using materials in technology, from data storage to electric motors.

Iron Group Elements in Magnetism

The iron group elements, which include iron (Fe), cobalt (Co), and nickel (Ni), are well-known for their ferromagnetic properties. This unique group of elements is central to the study of magnetism due to their ability to maintain a magnetic field even after an external field is removed.

- **Iron (Fe)**: Perhaps the most famous ferromagnetic element, widely used in magnets and magnetic alloys.
- **Cobalt (Co)**: Often used in high-temperature applications due to its stable magnetic properties.
- **Nickel (Ni)**: Known for its good magnetic properties and often used in alloys to enhance magnetic performance.

This group of elements is critical for advancing magnet technology, offering avenues for research into materials that can perform even under extreme conditions.

Applications of Ferromagnetic Materials

Ferromagnetic materials play a vital role in modern technology due to their magnetic properties. They are ubiquitous in many devices and applications.

- **Recording Media**: Chromium dioxide, a ferromagnetic oxide, finds extensive use in magnetic tapes and other media because of its stable ferromagnetic properties.
- **Motors and Generators**: These materials are used in the cores of electric motors and generators, thanks to their ability to maintain a magnetic field which is essential for the conversion of electrical energy into mechanical energy and vice versa.
- **Magnetic Storage**: Materials like iron and its alloys are critical in the development of hard disks and other storage media, allowing for the efficient and compact storage of data.

Their wide-ranging applications underline the importance of these materials in both everyday products and advanced technological innovations.